1. Field of the Invention
The subject invention relates to the making of tobacco rod, cigarette tobacco rod for example.
2. Brief Description of the Related Art
In the commercial manufacture of cigarettes, cigarette tobacco rod is conventionally made on a rod making machine, a machine supplied by, for example, G. D. S.p.A., Korber A G or Molins P L C. Such rod making machines comprise a hopper, a carding unit, a garniture and a cut-off device. In the operation of such a machine the hopper receives tobacco filler material and serves to hold a reservoir supply thereof. The carding unit receives tobacco filler material from the hopper and serves to disentangle entangled filler material and to provide an even supply of the filler material for feed to the garniture. Within the garniture the filler material is enwrapped in a web of cigarette paper, which paper is supplied from a bobbin thereof. There thus continuously exits the garniture a tobacco rod, which rod runs through the cut-off device, wherein the rod is severed to provide discrete sections of cigarette rod length.
Owing to the considerable degree of handling to which the tobacco filler material is subjected during the passage thereof through a rod making machine, the filler suffers degradation such that a proportion of the filler is of less than optimum or adequate particle size for the making of cigarette rod.
In the specification of U.S. Pat. No. 3,664,351 there is described a proposal for effecting a reduction in the degradation to which tobacco filler is subjected during the passage thereof through the garniture of a rod making machine. According to this proposal, the filler, after passing through the carding unit, is pneumatically transported, in an upward direction, through a narrow arcuate path to a suction band, which band serves to transport a carpet of the filler to the entry end of the garniture. During the passage of the filler through the said arcuate path the filler is subjected to microwave frequency heating, this being with a view to effecting an enhancement of the pliability of the tobacco particles and hence a reduction in the degree of degradation suffered by the filler during passage through the garniture.
The proposal of U.S. Pat. No. 3,664,351 is attended by a number of disadvantages. In that the arcuate path extending to the suction band is very narrow (8 mm), and in that there are direction changes at the entry and exit of the path (to prevent or reduce radiation escape), the provision of the path itself leads to degradation of the tobacco. Furthermore, the direction change at exit from the arcuate path causes blockages to occur and within a few seconds (not more than about ten) the tobacco in such a blockage becomes charred, i.e. it reaches a temperature of at least 700.degree. C. In that the tobacco filler is being microwave heated while being pneumatically transported in the arcuate path, heat is instantaneously lost from the tobacco to the transporting air. The walls of the arcuate path are in turn heated by contact with the air. It is thus part of the proposal of U.S. Pat. No. 3,664,351 that there is provided an electrically driven cooling fan.